This invention relates to a wheel bearing assembly for supporting a vehicle wheel, and particularly to an arrangement for providing a seal for between fitting surfaces of first and second inner members.
As a wheel bearing assembly for a driving wheel, one as shown in FIG. 9 is known. This wheel bearing assembly comprises an outer member 1, a first inner member 11 and a second inner member 21, and double-row rolling elements 31 for supporting the outer member 1 and the first and second inner members 11 and 21 so as to be rotatable relative to each other.
The outer member 1 has on its outer periphery a flange 2 for mounting to a vehicle body, and has on its inner periphery double-row raceways 3a, 3b. 
The first inner member 11 is formed on its outer periphery with a wheel-mounting flange 12 for supporting a driving wheel, and a raceway 13 opposing raceway 3a. Also, the first inner member 11 is formed with a stem-inserting hole 14 extending therethrough. The hole 14 comprises a fitting hole portion 14a and a spline hole portion 14b. 
The second inner member 21 comprises an outer joint member of a constant-velocity joint provided with a stem 23 at a closed end of its mouth portion 22. On an outer periphery of the second inner member 21, a raceway 27 is formed so as to oppose the raceway 3b. Also, the second inner member 21 has the stem 23 which is formed with a fitting shaft portion 23a fitted into the fitting hole portion 14a, and a spline shaft portion 23b fitted in the spline hole portion 14b. 
The stem 23 of the second inner member 21 is inserted in the stem-inserting hole 14 of the first inner member 11, and by caulking a tip of the stem 23 the first and second inner members 11 and 21 are coupled together. Numeral 26 shows a caulked portion.
Double-row rolling elements 31 are mounted between the double-row raceways 3a, 3b, and the raceways 13, 27, of the first and second inner members 11 and 21. By caulking the tip of the stem 23 with a pre-load applied between the double-row rolling elements 31 and the raceways 3a, 3b, 13, 27, the wheel bearing assembly is assembled.
Seal members 41 are mounted at both ends of the outer member 1 on its inner periphery. The seal members 41 provide a seal between the outer member 1 and the first and second inner members 11 and 21 to prevent muddy water and foreign matter from entering into the bearing assembly.
Automobiles, particularly RVs (recreational vehicles), provided with a conventional wheel bearing assembly sometimes travel on snow-covered roads, mountain roads and bad roads. In such a case, although a seal is provided between opposed portions of the outer member 1 and the first and second inner members 11 and 21 by the seal members 41, it is necessary to take measures to prevent entry of muddy water or dirt into the bearing assembly through fitting surfaces of the first inner member 11 and the second inner member 21.
An object of this invention is to provide a bearing assembly which is superior in sealing properties and prevents entry of muddy water, thereby increasing the life of the bearing assembly.
According to this invention, there is provided a wheel bearing assembly comprising an outer member having a flange, for mounting to a vehicle body, on an outer periphery of the outer member. The outer member is also formed with two raceways on its inner periphery. The wheel bearing assembly also comprises a first inner member having on its outer periphery a wheel-mounting flange and a raceway opposing one of the two raceways on the outer member, and a second inner member having on its outer periphery a raceway opposing the other of the two raceways. The second inner member is coupled to the first inner member, and double-row rolling elements are mounted between the outer member and the first and second inner members. The wheel bearing assembly also comprises a pair of seal members for providing a seal between both ends of the inner periphery of the outer member and the outer peripheries of the first and second inner members. And, the wheel bearing assembly further comprises a sealing member for providing a seal for between the first inner member and the second inner member.
By providing the sealing member for providing a seal for between fitting surfaces of the first and second inner members, it is possible to prevent entry of muddy water into the bearing assembly through a gap between the fitting surfaces. Thus, traveling on a bad road having much muddy water, in an RV will not lower the life of bearing assembly.
The sealing member may comprise a seal ring mounted in an annular groove formed in at least one of fitting surfaces between the first inner member. The seal ring is mounted in the annular groove so as to be in resilient contact with the other of the fitting surfaces. The sealing member may alternatively comprise a seal member mounted on one of opposed end faces of the first and second inner members, with the seam member having a plurality of seal lips in resilient contact with the other end face. With the sealing member comprising such a seal member, it is possible to provide a seal at contact portions between the plurality of seal lips and the other end face, and thus an extremely high degree of sealing is assured.
Also, the sealing member may comprise a seal cap mounted on one end of the second inner member protruding outwardly beyond an outer end face of the first inner member, with the seal cap having a seal lip in resilient contact with the outer end face of the first inner member to cover an opening of a hole formed in the first inner member. With this arrangement, since the seal cap can be mounted after the wheel bearing assembly has been assembled, assembling work is easy. Further, a sealing agent may be applied to fitting surfaces between the first and second inner members. By using such a sealing agent, it is possible to fill a gap at the fitting portion, and thus a high degree of sealing is achieved.
In the wheel bearing assembly according to this invention, the second inner member may be an outer joint member of a constant-velocity joint having a stem formed with a fitting shaft portion pressed into a fitting hole portion of a stem-inserting hole formed in the first inner member, and also formed with a spline shaft portion inserted into a spline hole portion of the stem-inserting hole. If the outer joint member is the second inner member, it is integrated with a constant-velocity joint, and thus it is possible to reduce weight and axial length of the wheel bearing assembly.
In the wheel bearing assembly according to this invention, the second inner member may be an inner ring pressed on a small diameter bearing ring fitting surface formed on the outer periphery of the first inner member at one end thereof.
Other features and objects of the present invention will become apparent from the following description made with reference to the accompanying drawings, in which: